The present disclosure relates to a method for regulating a battery voltage of a battery comprising a plurality of battery cells which can be selectively bridged and connected to a battery string, in which case, in the method, the battery voltage is regulated to a desired nominal voltage by alternately driving the battery cells. The disclosure also relates to a battery comprising at least one battery string with a plurality of battery cells which can be bridged and connected to the battery string by means of driving, recording means for recording operating parameters of the battery cells, and regulating electronics for regulating a battery voltage.
It is becoming apparent that battery systems will be increasingly used in future both in stationary applications and in vehicles such as hybrid and electric vehicles. In order to be able to meet the requirements imposed on voltage and available power for a respective application, a large number of battery cells are connected in series, thus forming a battery string which provides a battery voltage. In order to achieve a high battery current, battery cells are often additionally connected in parallel.
Previous applications by the applicant described batteries having a battery string with a variable or adjustable battery voltage. This was achieved by activating a particular number of battery cells or battery modules, with the result that their total voltage corresponds to a desired nominal value for a battery voltage, in which case the other battery cells which are not required are deactivated or bridged. According to the prior art, coupling circuits of the battery cells are driven by microcontrollers for this purpose, the microcontrollers typically communicating with a central controller across DC isolation. The coupling circuits may be implemented by means of semiconductor switches, in particular MOSFET transistors, and a respective associated driver circuit. The semiconductor switches may be arranged in a half-bridge configuration or a full-bridge configuration. Furthermore, each of the coupling circuits may be provided for the purpose of switching an individual battery cell or a battery module having a plurality of battery cells. In this case, a central controller must inform a respective coupling circuit, via a communication interface or a signal transmission connection (communication bus), whether the battery cell or battery module is intended to be connected or bridged and which transistor is intended to be switched on and which is not.
However, the large amount of communication effort which is required is disadvantageous; this occurs to a particularly large extent when the number of battery modules or battery cells respectively switched by a coupling unit is reduced in order to achieve fine voltage graduation of the battery voltage. The large amount of communication effort lies, in particular, in the requirement for the battery cells or battery modules to generally have to be addressed and switched in real time in order to obtain a sufficiently robust and efficient battery system.